1. Field of the Invention
The present invention relates to a color filter substrate including a unit pixel having a relatively large area, and to a color display device using the color filter substrate, such as a liquid crystal display device and an EL element.
2. Description of the Related Art
A liquid crystal display device that performs color display and a color display device using a PDP or an EL element have been put into practical use. In each of these display devices, for example, one unit pixel is formed of sub-pixels of three colors which are red (R), green (G) and blue (B), and multi-color display is performed by an additive color mixture. At this time, an area of the unit pixel is reduced, whereby a viewer is not allowed to individually recognize the respective sub-pixels. In such a way, the additive color mixture is enabled.
FIG. 13A is a perspective view schematically illustrating a state where a liquid crystal display device 100 including color filters is disassembled, and FIG. 13B is an explanatory view illustrating a layout of the color filters. In FIG. 13A, color filters 102 are formed on a lower substrate 101. The color filters 102 include stripe-like colored layers formed of respective colors of R, G and B, and black masks (BL) formed among these colored layers in order to prevent leakage of light. A planarization film 103 is formed on the color filters 102, and stripe-like transparent electrodes 104 are formed on the planarization film 103. The colored layers of R, G and B and the transparent electrodes 104 are patterned so as to have the same stripe-like shape. Opposing transparent electrodes 105 are formed on an inner surface of an upper substrate 106. A liquid crystal (not shown) is filled between the upper substrate 106 and the lower substrate 101, whereby a liquid crystal panel is formed. Further, a polarization plate (not shown) and a backlight (not shown) are arranged under the lower substrate 101, and a polarization plate (not shown) is disposed on the top surface of the upper substrate 106. This liquid crystal display device 100 applies voltages between the transparent electrodes 104 on the lower substrate 101 and the opposing transparent electrodes 105 on the upper substrate 106, and thereby changes molecular alignment directions of the liquid crystal. Then, the liquid crystal display device 100 visualizes this change of the molecular alignment direction of the liquid crystal by the polarization plates, and thereby performs display.
FIG. 13B illustrates a state of the color filters 102 on the lower substrate 101 when viewed from the above. Here, the transparent electrodes 105 formed on the inner surface of the upper substrate 106 are illustrated by dotted lines. The respective colored layers of R, G and B are arranged regularly. Each intersecting portion of the colored layers of R, G and B and the opposing transparent electrodes 105, that is, a region surrounded by a broken line of FIG. 13B is a unit pixel 107. Hence, regions of the respective colored layers in the region surrounded by the broken line illustrating the unit pixel 107 correspond to the sub-pixels. The voltages are applied between the transparent electrodes 104 and the opposing transparent electrodes 105, whereby quantities of light that passes through the color filters are changed independently for each of the colors. In such away, the viewer who views the light transmitted through the color filters is able to view a color image subjected to the additive color mixture.
In the above-mentioned conventional example, the respective color filters are formed of the stripe-like colored layers, and the unit pixel has the respective rectangular colored layers arranged in parallel therein. As opposed to this, in color filters 102 illustrated in FIG. 14, adjacent colored layers are formed so as to engage with one another (for example, refer to Japanese Utility Model Application Laid-open No. Sho 60-21723). The respective colored layers are formed into the stripe shape, formed so as to have projection/depression portions in plan view, and formed so that the projection/depression portions of the adjacent colored layers can engage with one another. A broken line of FIG. 14 forms a unit pixel 108, and has a triangular shape. Likewise, in each of JP 2002-221917 A and JP 2005-62416 A, a layout of color filters is described, in which the respective sub-pixels have a triangular or hexagonal shape, and unit pixels are arranged in delta.
In a liquid crystal display device for use in a usual notebook computer, a length L1 or L2 of one side of the unit pixel 107 is 100 to 180 μm. A width of each of the colored layers of the unit pixel 107 is approximately 30 to 50 μm. Hence, an area of the unit pixel 107 is approximately 0.01 to 0.03 mm2. Further, when a longitudinal centerline of such a colored layer of R is defined as Cr, and likewise, a centerline of a colored layer of G is defined as Cg, and a centerline of a colored layer of B is defined as Cb, a distance D between the centerlines Cr and Cg becomes approximately 30 to 60 μm, and a distance between the centerlines Cr and Cb becomes approximately 60 to 120 μm.
By means of eyesight of 1.0 in accordance with the Landolt ring, a gap of 1.5 mm can be recognized from a position apart therefrom by 5 m. Specifically, a minimum gap recognizable to be separated when being viewed by a viewer with the eyesight of 1.0 from a point apart therefrom by 50 cm is approximately 150 μm, and a minimum gap when being viewed by the same viewer from a point apart therefrom by 60 cm is approximately 180 μm. In the liquid crystal display device using the color filters having the conventional configuration, a distance between the centerline Cr of the colored layer of R and the centerline Cb of the colored layer of B located while interposing the colored layer of G therebetween is approximately 150 μm at the maximum, in other words, when the viewer with the eyesight of 1.0 views the display screen from the point apart therefrom by 50 cm, a distance between the centerline Cr of the colored layer of R and the centerline Cb of the colored layer of B located while interposing the colored layer of G therebetween is 150 μm at the maximum. Accordingly, the regions of the respective colored layers cannot be visually recognized to be separated from one another, and the viewer will view a color obtained by the additive color mixture. Hence, the viewer can view the image without being conscious of the colored regions of the respective colors, which form the unit pixel. The same also applies to a PDP display device, an EL display device or a reflection-type display device as well as the liquid crystal display device.
However, in the case of performing the color display on a display device in which an alignment pitch of such unit pixels is coarse and an area of each unit pixel is large, the additive color mixture is not performed with the conventional configuration of the unit pixel, and display quality of the display device is decreased. For example, in the case where the pitch of the colored layers forming the unit pixel exceeds 150 μm and the area of the unit pixel is 0.1 mm2 or more, there has been a problem that the additive color mixture is not performed in the unit pixel because the respective colored layers look separated from each other.